The Hoffmann kiln is a series of batch process kilns. Hoffmann kilns are the most common kiln used in production of bricks and some other ceramic products. Patented by German Friedrich Hoffmann for brickmaking in 1858, it was later used for lime-burning, and was known as the Hoffmann continuous kiln.
A Hoffmann kiln consists of a main fire passage surrounded on each side by several small rooms. Each room contains a pallet of bricks. In the main fire passage there is a fire wagon, that holds a fire that burns continuously. Each room is fired for a specific time, until the bricks are vitrified properly, and thereafter the fire wagon is rolled to the next room to be fired.
Each room is connected to the next room by a passageway carrying hot gases from the fire. In this way, the hottest gases are directed into the room that is currently being fired. Then the gases pass into the adjacent room that is scheduled to be fired next. There the gases preheat the brick. As the gases pass through the kiln circuit, they gradually cool as they transfer heat to the brick as it is preheated and dried. This is essentially a counter-current heat exchanger, which makes for a very efficient use of heat and fuel. This efficiency is a principal advantage of the Hoffmann kiln, and is one of the reasons for its original development and continued use throughout history. [1] In addition to the inner opening to the fire passage, each room also has an outside door, through which recently fired brick is removed, and replaced with wet brick to be dried and then fired in the next firing cycle.
In a classic Hoffmann kiln, the fire may burn continuously for years, even decades; in Iran, there are kilns that are still active and have been working continuously for 35 years. Any fuel may be used in a Hoffmann kiln, including gasoline, natural gas, heavy petroleum and wood fuel. The dimensions of a typical Hoffmann kiln are completely variable, but in average about 5 m (height) x 15 m (width) x 150 m (length).
The first kiln of this class was put into operation on November 22, 1859 [2] in Scholwin (since 1946, Skolwin), [3] near Stettin, which was then part of Prussia. In 1867 there were already 250 of them, most in the Prussian part of Germany, fifty in England and three in France. In Italy, their expansion began in 1870, after being shown at the Paris Exhibition. [4] In September 1870, the first brick factory according to Hoffmann's patent was inaugurated in Australia. [5] The first continuous Hoffmann system kilns installed in Spain would have been in 1880, near Madrid. [6] In 1900 there were already more than 4,000 kilns of this type, distributed throughout Europe, Russia, the Americas, Africa and even the East Indies. [7] In 1904, an oven according to the patent of the British William Sercombe and based on the Hoffmann model began operating in Palmerston North, New Zealand. [8] Hoffman kilns are still in use for brick production in some parts of the world, especially in places where labor costs are low and modern technology is not easily accessible.
The Hoffmann kiln is used in almost every country.
In the British Isles there are only a few Hoffmann kilns remaining, some of which have been preserved. [9]
The only ones with a chimney are at Prestongrange Industrial Heritage Museum and Llanymynech Heritage Area. The site at Llanymynech, close to Oswestry was used for lime-burning and has recently been partially restored as part of an industrial archaeology conservation project supported by English Heritage and the Heritage Lottery Fund. [9]
Two examples in North Yorkshire, the Hoffmann lime-burning kiln at Meal Bank Quarry, Ingleton, and that at the former Craven and Murgatroyd lime works, Langcliffe, are scheduled ancient monuments. [10] [11]
There is an intact but abandoned Hoffmann kiln without a chimney present at Minera Limeworks; the site is abandoned but all entrances to the kiln have been grated-off, preventing access. The kiln is in a very poor state of repair, with trees growing out of the walls and the roof. Minera Quarry Trust hopes one day to develop the area into something of a tourist attraction. The Grade II listed Hoffmann brick kiln in Ilkeston, Derbyshire, is also badly neglected, although the recently installed fencing offers some protection for the building and for visitors. [12]
At Prestongrange Museum, outside Prestonpans in East Lothian, the Hoffman kiln is still standing and visitors can listen to more about it via a mobile phone tour. [13]
There is a nearly complete kiln in Horeb, Carmarthenshire. [13]
There is still a working kiln at Kings Dyke in Peterborough, which is the last site of the London Brick Company, owned by Forterra PLC.[ citation needed ]
In Victoria, Australia, at the Brunswick brickworks, there are two surviving kilns converted to residences, and a chimney from a third kiln; there is another in Box Hill, Victoria; also in Melbourne. [14]
In Adelaide, South Australia, the last remaining Hoffman kiln in the state is in at the old Hallett Brickworks site in Torrensville. [14] [15] [16]
There is one at St Peters in Sydney, New South Wales. [14]
In Western Australia, the kiln at the Maylands Brickworks in the Perth suburb of Maylands, which operated from 1927 to 1982 is the only remaining Hoffman kiln in the state. [17]
There is a complete kiln in the restored Tsalapatas brick Factory in Volos Greece that has been converted to an industrial museum. [19]
There are two in New Zealand.[ citation needed ]
Kaohsiung city in Taiwan is also home to a Hoffman kiln, built by the Japanese government in 1899. [20] [ circular reference ]
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, tiles and bricks. Various industries use rotary kilns for pyroprocessing and to transform many other materials.
A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide). The chemical equation for this reaction is
Llanymynech is a village and former civil parish straddling the border between Montgomeryshire/Powys, Wales, and Shropshire, England, about 9 miles (14 km) north of the Welsh town of Welshpool. The name is Welsh for "Church of the Monks". The village is on the banks of the River Vyrnwy, and the Montgomery Canal passes through it.
A brickworks, also known as a brick factory, is a factory for the manufacturing of bricks, from clay or shale. Usually a brickworks is located on a clay bedrock, often with a quarry for clay on site. In earlier times bricks were made at brickfields, which would be returned to agricultural use after the clay layer was exhausted.
Mortdale is a suburb located in southern Sydney, in the state of New South Wales, Australia. Mortdale is located 20 kilometres south of the Sydney central business district and is part of the St George area. Mortdale is situated in the local government area of Georges River Council. Mortdale extends south to Lime Kiln Bay, on the Georges River. Mortdale Heights is a locality in the western corner of the suburb.
Penwyllt is a hamlet located in the upper Swansea Valley in Wales. It lies within a part of the Brecon Beacons National Park in the traditional county of Brecknockshire; currently administered as part of the unitary authority of Powys.
Prestongrange Museum is an industrial heritage museum at Prestongrange between Musselburgh and Prestonpans on the B1348 on the East Lothian coast, Scotland. Founded as the original site of the National Mining Museum, its operation reverted to East Lothian Council Museum Service in 1992.
Bradford Colliery Brickworks operated on the site of the Bradford Colliery in Bradford, Manchester, then in the historic county of Lancashire, England, between the early 1870s and 1903. To exploit the seams of fire clay found between the coal seams, colliery manager Edward Williams built a large kiln to a design patented in 1870 by Friedrich Hoffmann, which permitted the continuous production of bricks. One of the largest brick-making facilities in the area, the kiln was more than 30 metres (98 ft) long and 17 metres (56 ft) wide, and probably contained 12–14 separate firing chambers.
Cocking Lime Works and its associated chalk quarry are abandoned industrial sites in the South Downs of England. They are to the south of the village of Cocking, West Sussex, close to the South Downs Way. The works are on land owned by the Cowdray Estate and are not open to the public. Cocking was the source of lime used for the manufacture of Midhurst White bricks and for agricultural purposes.
Llanymynech Heritage Area is an historic former lime kiln, quarry and industrial site near the village of Llanymynech, Shropshire in the Welsh Marches. The site is adjacent to the A483 road and close to the Montgomery Canal. It is about 6 miles (10 km) south of Oswestry on the English side of the border, and about 9 miles (14 km) north of the Powys town of Welshpool.
The Brunswick Brick Tile & Pottery Company was established in 1870 on a 12-acre paddock on Albert Street Brunswick, as one of the first modern mechanical brickworks in Australia. It was also known as the Hoffman Patent Brick & Tile Company, Hoffman Brickworks, or just ' Hoffman's' for most of its 100 plus years of operation.
Newmarket Brickworks Chimney is a heritage-listed brickworks at 117 Mina Parade, Alderley, City of Brisbane, Queensland, Australia. It was built in 1912. It is also known as Hoffman Stack. It was added to the Queensland Heritage Register on 24 March 2000.
Pindi Pindi Brickworks is a heritage-listed former brickworks off the Bruce Highway, Pindi Pindi, Mackay Region, Queensland, Australia. It was built in 1933. It is also known as Evans Firebricks Ltd and Pindi Pindi Firebricks Company. It was added to the Queensland Heritage Register on 27 October 2000.
Porth Wen Brickworks first built by Charles E Tidy, is now a disused Victorian brickworks which produced fire bricks, made from quartzite (silica) used to line steel-making furnaces. The substantial remains include a number of buildings and the remains of some of the machinery, but has some damage from sea erosion. The site is a scheduled monument.
The Brickworks Museum, also known as Bursledon Brickworks, is a volunteer-run museum in Swanwick, Hampshire, England. It is purportedly the UK's sole surviving Victorian steam-driven brickworks.
Llanymynech and Pant is a civil parish in Shropshire, England. It contains 23 listed buildings that are recorded in the National Heritage List for England. All the listed buildings are designated at Grade II, the lowest of the three grades, which is applied to "buildings of national importance and special interest". The parish contains the villages of Llanymynech and Pant, and the surrounding area. The border between England and Wales passes through Llanymynech, and this is marked by a boundary stone which is listed. The area was once important for the manufacture of lime, and seven groups of lime kilns are listed, together with the much larger Hoffmann Kiln and its chimney. In Llanymynech is a listed pair of houses, a public house, and a church together with a pair of gate piers, and a memorial in the churchyard. Elsewhere, the listed buildings include farmhouses, farm buildings, an ice house, a gin wheel, a former mill, and a canal bridge.
The Lithgow Valley Colliery and Pottery Site is a heritage-listed former pottery and colliery and now pottery and visitor attraction at Bent Street, Lithgow, City of Lithgow, New South Wales, Australia. It was built from 1876 to 1945. It is also known as Lithgow Pottery and Brickworks. The property is privately owned. It was added to the New South Wales State Heritage Register on 2 April 1999.
Raffan's Mill and Brick Bottle Kilns is a heritage-listed lime kiln at Carlton Road, Portland, New South Wales, Australia. It was built from 1884 to 1895 by George Raffan and Alexander Currie. It is also known as Raffan's Mill and Brick Bottle Kilns Precinct, Portland Cement Works Site, Williwa Street Portland. The property is owned by Boral. It was added to the New South Wales State Heritage Register on 3 August 2012.
Betchworth Quarry and Lime Kilns is a 27-hectare (67-acre) nature reserve north of Betchworth in Surrey. Betchworth Quarry only is managed by Surrey Wildlife Trust. It is part of the Mole Gap to Reigate Escarpment Site of Special Scientific Interest and Special Area of Conservation.
Maylands Brickworks is a historical brickworks factory in Maylands, Western Australia. It operated between 1927 and 1983.
September 2008: Published online with revised contact details: Department for Environment and Heritage 2008
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